import java.util.Scanner;

/**
   Determines the average number of characters for words in a string.   
   Input: a string of one or more lines containing words
   Output: the average number of characters per word in the string 
      to two decimal places
*/
public class WordAvg
{
   public static void main(String[] args)
   {
      Scanner in = new Scanner(System.in);

      // your work here
      double words = 0.0;
      double chars = 0.0;

      while (in.hasNext())
      {
         String word = in.next();

         // more work here
         words += 1.0;
         chars += word.length();


      }

      // more work here
      double average = chars / words;
      System.out.printf("%.2f\n", average);
   }
}